UV LED packages include UV LED chips emitting UV light at wavelengths of 200 nm to 400 nm and are used in various applications, such as sterilizers. Such UV LED chips emit UV light at much shorter wavelengths than a blue wavelength region. Due to a strong energy of UV light, a large amount of heat is released from the UV LED chips.
A typical conventional UV LED package uses a flip-chip UV LED chip. The conventional UV LED package includes a package body including two lead electrodes separated from each other by an electrode separation line. The UV LED chip includes two downwardly pointing bonding pads that are mounted on the package body by direct flip-chip bonding to corresponding lead electrodes. The UV LED chip is flip-chip bonded only in a limited direction. Specifically, first and second flip-chip bonding pads or first and second bonding bumps of the UV LED chip are arranged orthogonal to the electrode separation line.
The conventional UV LED package is difficult to design for abnormal overheating so long as the UV LED chip is not large in an area. Despite this difficulty, the UV LED chip is usually limited to a small area, and as a result, heat from the bonding pads of the UV LED chip is not efficiently delivered to the lead electrodes of the package body, resulting in a poor heat dissipation efficiency. Thus, the lifetime of the conventional UV LED package is shortened by heat generated when the UV LED chip emits UV light at short wavelengths of 200 to 400 nm, particularly 270 to 285 nm.
Another problem of the UV LED package is that due to a narrow width of the electrode separation line (that is, the small distance between the lead electrodes), bonding materials (i.e., soldering materials) may remain unseparated and adhere to each other during flip-chip bonding of the UV LED chip, increasing the risk of short-circuiting. Also, see a related art disclosed in a Korean Patent Application No. 10-1349701, filed Jan. 3, 2014.
A large portion of the package body of the UV LED package other than the lead electrodes is made of a resin. This increases the risk that UV light may cause the package body to crack or discolor. Hence, there is a need for an improved UV LED package addressing at least these shortcomings.